Bo Dependence of the On-Resonance Longitudinal Relaxation Time in the Rotating Frame (T1ρ) in Protein Phantoms and Rat Brain in Vivo

Heidi I. Mäkelä; Enrico De Vita; Olli H.J. Gröhn; Mikko I. Kettunen; Martin Kavec; Mark Lythgoe; Michael Garwood; Roger Ordidge; Risto A. Kauppinen

doi:10.1002/mrm.10669

B_o Dependence of the On-Resonance Longitudinal Relaxation Time in the Rotating Frame (T_1ρ) in Protein Phantoms and Rat Brain in Vivo

Heidi I. Mäkelä, Enrico De Vita, Olli H.J. Gröhn, Mikko I. Kettunen, Martin Kavec, Mark Lythgoe, Michael Garwood, Roger Ordidge, Risto A. Kauppinen

Center for Magnetic Resonance Research

Research output: Contribution to journal › Article › peer-review

22 Scopus citations

Abstract

On-resonance longitudinal relaxation time in the rotating frame (T _1ρ) has been shown to provide unique information during the early minutes of acute stroke. In the present study, the contributions of the different relaxation mechanisms to on-resonance (T_1ρ), relaxation were assessed by determining relaxation rates (R_1ρ) in both protein phantoms and in rat brain at 2.35, 4.7, and 9.4 T. Similar to transverse relaxation rate (R₂), R_1ρ increased substantially with increasing magnetic field strength (B_o). The B_o dependence was more pronounced at weak spin-lock fields. In contrast to R_1ρ, longitudinal relaxation rate (R₁) decreased as a function of increasing B_o field. The present data argue that dipole-dipole interaction forms only one pathway for T _1ρ, relaxation and the contributions from other physicochemical factors need to be considered.

Original language	English (US)
Pages (from-to)	4-8
Number of pages	5
Journal	Magnetic resonance in medicine
Volume	51
Issue number	1
DOIs	https://doi.org/10.1002/mrm.10669
State	Published - Jan 2004

Keywords

Brain
Dipole-dipole interaction
Relaxation
T

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title = "Bo Dependence of the On-Resonance Longitudinal Relaxation Time in the Rotating Frame (T1ρ) in Protein Phantoms and Rat Brain in Vivo",

abstract = "On-resonance longitudinal relaxation time in the rotating frame (T 1ρ) has been shown to provide unique information during the early minutes of acute stroke. In the present study, the contributions of the different relaxation mechanisms to on-resonance (T1ρ), relaxation were assessed by determining relaxation rates (R1ρ) in both protein phantoms and in rat brain at 2.35, 4.7, and 9.4 T. Similar to transverse relaxation rate (R2), R1ρ increased substantially with increasing magnetic field strength (Bo). The Bo dependence was more pronounced at weak spin-lock fields. In contrast to R1ρ, longitudinal relaxation rate (R1) decreased as a function of increasing Bo field. The present data argue that dipole-dipole interaction forms only one pathway for T 1ρ, relaxation and the contributions from other physicochemical factors need to be considered.",

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AU - Mäkelä, Heidi I.

AU - De Vita, Enrico

AU - Gröhn, Olli H.J.

AU - Kettunen, Mikko I.

AU - Kavec, Martin

AU - Lythgoe, Mark

AU - Garwood, Michael

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AB - On-resonance longitudinal relaxation time in the rotating frame (T 1ρ) has been shown to provide unique information during the early minutes of acute stroke. In the present study, the contributions of the different relaxation mechanisms to on-resonance (T1ρ), relaxation were assessed by determining relaxation rates (R1ρ) in both protein phantoms and in rat brain at 2.35, 4.7, and 9.4 T. Similar to transverse relaxation rate (R2), R1ρ increased substantially with increasing magnetic field strength (Bo). The Bo dependence was more pronounced at weak spin-lock fields. In contrast to R1ρ, longitudinal relaxation rate (R1) decreased as a function of increasing Bo field. The present data argue that dipole-dipole interaction forms only one pathway for T 1ρ, relaxation and the contributions from other physicochemical factors need to be considered.

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